1. Field of the Invention
The present invention relates to an imaging display system, or more particularly, to an imaging display system for transmitting picture information acquired by an imaging apparatus to a display apparatus and for displaying a picture.
2. Description of the Related Art
In the past, a picture display method for displaying a motion picture which is implemented in a TV conference system or the like has employed various means for the purpose of reducing a total amount of information to be transmitted.
For example, Japanese Unexamined Patent Publication No. 2-107087 describes a picture display method to be implemented in a motion picture display system having a transmission apparatus for transmitting picture information input from a video input unit while storing it screen by screen in a memory, and a display apparatus for receiving the picture information from the transmission apparatus, storing it screen by screen in a memory, and then displaying it on a display unit. Herein, the transmission apparatus includes a transmitting means for transmitting whole picture information of a specific screen and picture information of given portions of the other screens in units of a plurality of screens stored in the memory. The display apparatus includes a means for outputting whole picture information of the specific screen out of all picture information stored in the memory to the display apparatus, and outputting picture information of the given portions of the other screens to the display unit, or synthesizing picture information of the other portions of the other screens and picture information of the specific screen and then outputting synthetic information to the display unit. Picture information input from the video input unit is displayed as a motion picture in units of the plurality of screens.
In this kind of system, for reading image data from a memory means in a transmission apparatus having the capability of an imaging apparatus, picture information of a portion of a screen depicting many motions is extracted and transmitted. As for a portion of the screen depicting few motions, information of a partial screen received in advance by a receiving side is utilized. Thus, even when an amount of information to be transmitted is reduced, an easy-to-see picture depicting smooth motions can be displayed.
However, in the system described in the Japanese Unexamined Patent Publication No. 2-107087, a memory means is included in the imaging apparatus having the capability of a transmission apparatus. This poses a problem that the imaging apparatus becomes large in size and costs more.
Moreover, a means is included for optimizing the way of outputting pixel data that has been written in the memory means. However, no measures are taken to reduce an amount of information which affects writing of an output of an imaging device in the memory means. That is to say, when an imaging device that cannot be accessed randomly, such as, a CCD is employed, it is necessary to output data of all pixels from the imaging device and write the data in the memory means. This leads to a longer time required for processing and to eventually a lowered frame rate. This poses a serious problem in the recent situation in which more and more imaging devices are enjoying a higher density of pixels.
Furthermore, when a range in a screen in which a subject makes motions is large or data of a whole screen is transmitted, it cannot be said that satisfactory measures are taken to reduce an amount of information to be transmitted.
Japanese Unexamined Patent Publication No. 6-350906 describes a picture signal synthesizing method in which an imaging device or an optical image formed on the imaging device is shifted in units of an integral submultiple of a pixel pitch in synchronization with a field or frame that means the time required for transmitting one half or a whole of a picture; n fields or frames, each of which means one half or a whole of a picture, produced by sampling n different sampled areas using one pixel opening during n fields or n frames are synthesized in order to produce a high-definition input picture. Herein, a luminance level of each sampled area is determined as a function of a sampled value of the sampled area relative to a sampled value of another sampled area to be sampled using the pixel opening designed to sample the sampled area.
In other words, according to the method described in the Japanese Unexamined Patent Publication No. 6-350906, partial pictures are produced while the imaging device is shifted, and then synthesized. Thus, using an imaging device having an ordinary number of pixels and having been used for multiple purposes in the past, a high-definition picture can be produced.
However, according to the method described in the Japanese Unexamined Patent Publication No. 6-350906, a means for shifting the imaging device is needed. This invites an increase in size of the imaging apparatus.
Furthermore, Japanese Unexamined Patent Publication No. 9-135390 describes an imaging apparatus comprising an imaging device having a light-receiving device area composed of a plurality of pixels, and an imaging device driving means for reading an optical charge signal from the imaging device. The imaging apparatus can switch a first driving mode, in which the driving means operates in a driving mode that is intended to utilize a signal output read from the imaging device instead of storing the output, into a second driving mode in which the driving means operates in a driving mode that is intended to record a signal read from the imaging device, or vice versa. In the first driving mode, data is read from part of the light-receiving device area. In the second driving mode, data is read from a light-receiving device area that is different at least partly from the light-receiving device area whose data is read in the first driving mode.
To be more specific, the imaging apparatus described in the Japanese Unexamined Patent Publication No. 9-135390 has the ability to select any one of block scan driving, skip scan driving, and all-pixel scan driving as a technique according to which the imaging device is driven by the imaging device driving means. For monitoring a subject using a display means, a driving technique permitting a high frame rate is selected. For imaging the subject, a technique for producing a high-definition picture, though a frame rate is low is adopted.
In the imaging apparatus described in the Japanese Unexamined Patent Publication No. 135390, it is hard to produce a high-definition picture at an ordinary frame rate. Moreover, there is difficulty in transmitting a high-definition picture produced at an ordinary frame rate to a display apparatus using a general-purpose communication means or the like. This is because a speed at which pictures are transmitted (or input or displayed) has its limitations, and as far as a high-definition picture is concerned, since an amount of information is large, a frame rate is lowered.
A conceivable configuration is such that a plurality of imaging apparatuses having relatively narrow fields of view are included for fine observation of an object. In this case, the plurality of imaging apparatuses must be viewed, and a plurality of recording means are needed for recording. The configuration is unsuitable for looking at a picture covering a whole field of view.
By the way, an imaging apparatus capable of producing a high-definition picture at a relatively high frame rate and outputting it as a motion picture has a special configuration and is therefore expensive. Moreover, when an imaging apparatus is designed to remotely transmit a high-definition picture at a relatively high frame rate, a special data line and input and output circuits for a network are needed. The imaging apparatus therefore becomes expensive.
In recent years, there has been a demand for the advent of an imaging display system designed for the purpose of, especially, monitoring and making it possible to view a motion picture produced at a high frame rate in a normal situation, to look at a high-definition picture if necessary, and to observe a dark subject clearly.